Editing ISSN (section)

== Code assignment, maintenance and look-up ==
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ISSN codes are assigned by a network of ISSN National Centres, usually located at [[national library|national libraries]] and coordinated by the '''ISSN International Centre''' based in [[Paris]]. The International Centre is an [[intergovernmental organization]] created in 1974 through an agreement between [[UNESCO]] and the French government.

=== Linking ISSN ===
''ISSN-L'' is a [[unique identifier]] for all versions of the serial containing the same [[content (media)|content]] across different media. As defined by ''ISO 3297:2007'', the "linking ISSN (ISSN-L)" provides a mechanism for collocation or linking among the different media versions of the same continuing resource. The ''ISSN-L'' is one of a serial's existing ISSNs, so does not change the use or assignment of "ordinary" ISSNs;<ref>{{cite web |author= |title=Linking ISSN (ISSN-L) |url=http://www.nationallibrary.fi/publishers/issn/issnl.html |url-status=dead |archive-url=https://web.archive.org/web/20150926075657/http://www.nationallibrary.fi/publishers/issn/issnl.html |archive-date=26 September 2015 |access-date=23 December 2018 |website=www.nationallibrary.fi}}</ref> it is based on the ISSN of the first published medium version of the publication. If the print and online versions of the publication are published at the same time, the ISSN of the print version is chosen as the basis of the ''ISSN-L''.

With ''ISSN-L'' is possible to designate one single ISSN for all those media versions of the title. The use of ''ISSN-L'' facilitates search, retrieval and delivery across all media versions for services like [[OpenURL]], [[library catalogue]]s, [[search engine]]s or [[knowledge base]]s.

=== Register ===
The International Centre maintains a database of all ISSNs assigned worldwide, the ''ISDS Register'' (International Serials Data System), otherwise known as the ''ISSN Register''. {{As of|2016|12|31|alt=At the end of 2016,}} the ISSN Register contained records for 1,943,572 items.<ref>{{cite web |title=Total number of records in the ISSN Register |url=https://www.issn.org/wp-content/uploads/2017/02/Total-records-in-Register.pdf |publisher=ISSN International Centre |access-date=23 February 2017 |date=February 2017 |archive-date=24 February 2017 |archive-url=https://web.archive.org/web/20170224055145/http://www.issn.org/wp-content/uploads/2017/02/Total-records-in-Register.pdf |url-status=live }}</ref> The Register is not freely available for interrogation on the web, but is available by subscription.

* The print version of a serial typically will include the ISSN code as part of the publication information.
* Most serial websites contain ISSN code information.
* Derivative lists of publications will often contain ISSN codes; these can be found through on-line searches with the ISSN code itself or serial title.
*[[WorldCat]] permits searching its catalog by ISSN, by entering "issn:" before the code in the query field. One can also go directly to an ISSN's record by appending it to "{{code|https://www.worldcat.org/ISSN/}}", e.g. [https://www.worldcat.org/ISSN/1021-9749 n2:1021-9749 – Search Results]. This does not query the ISSN Register itself, but rather shows whether any WorldCat library holds an item with the given ISSN.
<!-- Though an [https://www.issn.org:8080/English/pub/faqs/issn/issnchecking ISSN checking facility] {{Dead link|date=July 2022}} is available, this is a tool for checking the validity of an ISSN number format, not for querying the ISSN Register to determine what serial the input number is associated with. -->